Appendectomy in mid and later life and risk of Parkinson's disease: A population-based study.

INTRODUCTION Pathogenic movement of alpha-synuclein from the gut to the brain in PD has been proposed. The appendix has a relatively high density of alpha-synuclein deposition in neurologically healthy individuals. We investigated the incidence of PD after appendectomy. METHODS Using cause-specific hazards regression models, we compared persons over 35 years of age who had undergone appendectomy with two groups of age- and sex-matched individuals having had: (1) a cholecystectomy and (2) neither procedure. Subsequent diagnoses of PD were identified. RESULTS Among 42,999 individuals undergoing appendectomy, no difference in risk of PD was identified compared to cholecystectomy (hazard ratio = 1.004; 95% confidence interval: 0.740-1.364). Compared with no procedure, individuals with appendectomy had a higher incidence of PD within 5 years, but no significant difference in risk thereafter. CONCLUSION In our study, appendectomy in mid or late life does not appear to be associated with a reduced risk of PD. © 2016 International Parkinson and Movement Disorder Society.